While the present invention is broadly directed toward animals capable of nitrogen fixation, it is particularly useful in the control of termites. The prior art is generally cognizant of a wide variety of compounds which are useful either for introduction into wood for preserving the wood fiber from terminate infestation, of for directly controlling termites. Wood infestation and destruction by termites is a widely recognized problem, particularly in tropical and sub-tropical areas of the world and much research has been directed toward methods and compositions for controlling termite activity. Generally, in the prior art, it has been the practice to use either general organic insecticides or toxic metallic compounds to control or to kill termites. These compositions may be utilized directly to control termites by incorporated in a bait or attractant composition, but are typically utilized by injection or saturation in wood members so as to preserve wood which may come in contact with termite colonies.
Exemplary of the prior art illustrating the use of general organic insecticides against termites is the disclosure of U.S. Pat. No. 3,070,495, which describes the use of a decayed wood extract as a termite attractant so that the termites can be controlled by a conventional general organic insecticide, such as DDT, dieldrin, chlordane, parathion, malathion or others. Other examples are known in the art of packaging techniques for including such organic pesticides in baits, traps, or other devices intended to attract termites.
The use of several metallic compounds have been proposed or disclosed for termite control. U.S. Pat. No. 2,784,139 discloses a composition for preserving wood including, as a mycocidal and insecticidal ingredient, one of a variety of metal compounds including chromated zinc chloride, copper sulphate, arsenic compounds, and mercury compounds. Similarly U.S. Pat. No. 2,886,486 discloses a wood impregnating compound including therein chromated zinc sulphate. More recently, the disclosure of U.S. Pat. No. 3,832,463 illustrates the use of hexavalent chromium in a wood treating composition intended to preserve wood from microbial and insecticidal activity. It has also been proposed, in accordance with the disclosure of U.S. Pat. No. 3,993,752, to utilize an alkali metal cyanide added to a liquid fungicide including organic or inorganic sales of mercury, lead, tin, copper, or zinc to provide a wood treating composition having fungicidal and bactericidal properties. Further, it has been disclosed, in U.S. Pat. No. 4,132,780, that certain azide and metal salt formulations, including salts of iron, aluminum, nickel, maganese, colbalt, zinc, tin, or magnesium are capable of being used to control fungi and other micro-organisms.
It has been proposed, in one known teaching in the prior art, to utilize molybdenum in a composition claimed to have biological activity. In the disclosure of U.S. Pat. No. 2,025,405, a method for producing a water soluble colloidal molybdenum compound contains valuable "pharmaceutical and bacteriological" properties. In addition, U.S. Pat. Nos. 3,290,343 and 3,317,571 disclose certain compounds including molybdenum which are recited to be biologically active having use as pesticides.
It has been known and understood for some time that a very small number of animals, including termites and shipworms, are capable of nitrogen fixation, in a fashion analogous to the nitrogen fixation of legumes. The animals themselves actually do not fix nitrogen. Instead, it has been discovered that among the microflora living in symbiotic relationship in the gut of termites are some capable of nitrogen fixation and they supply nitrogen in a fixed form to the host termite for protein synthesis. For example, Benemann in "Nitrogen Fixation in Termites", Science, Volume 181, page 164, July 13, 1973, discusses the phenomenon of nitrogen fixation in termites and suggests that the nitrogen-fixing agent is the intestinal bacterial flora of the termites. It is assumed that these symbiotic bacteria in the termite gut play an essential role in the nutrition of these insects since the wood used as food for the termite is very low in nitrogen. Another pest species that lives in and feeds n wood is the shipworm, a mollusk that is responsible for significant damage to wood in marine environments. The shipworm also supports large numbers of nitrogen fixing bacteria in its intestines, Carpenter et al., "Nitrogen Fixation in Shipworms", Science, Volume 187, pps. 551-552, 1975.
It is known that among the nitrogen-fixing bacteria symbiotic with legumes, the enzyme nitrogenase, which is the enzyme responsible for nitrogen fixation, requires several atoms of molybdenum to be effective. It has been disclosed in literature that tungsten competes with molybdenum and may serve as an antagonist of molybdenum in the formation of this enzyme, Nagatani and Brill, "The Effect of Mo, W, and V on the Synthesis of Nitrogenase Components in Azotobacter vinelandii", Bioch. et Biophys. Acta, 362, 160-166 (1974).